Pump



AMay 4, 1937. A. o. MCCOLLUM '2,079,375

PUMP Filed June 9, 1936 ATTORNEY.

Patented May 4, 1937 UNITED STATES PUMP` Andrew 0. McCollum, Detroit, Mich., assigner of one-half to Oria H. McCollum, Detroit, Mich.

Application June 9, lssaserial No.y 84,345 2 claims. i(ci. 10s-120) This invention relates to a pump and more particularly to a pump adapted to deliver a supply of liquid under a variable pressure at constant speeds of the pump, or to deliver a constant supply of liquid at variable speeds of the pump.

In certain applications of a pump, as for example where the consumption of the liquid supplied is variable, it is desirable to supply the liquid in such quantities as is used thus necessitating a variable supply of liquid at constant speeds of the pump. In other instances it is desirable to maintain a constant pressure of the liquid while the speed of the pump is variable, as for example in the oil'pump of an internal combustion engine when a constant pressure on the bearings is desired. However, it is sometimes desirable to vary the pressure of the liquid in proportion to the speed of the pump, as a greater pressure may be required at higher speeds than at lower speeds.

Heretofore by-passes or relief valves have been used and in some cases specially designed valves have been used in the by-pass passage to obtain variable supplies at constant speeds or constant supplies at variable speeds. Such devices are expensive and necessitate many parts particularly where a variable pressure in proportion to a variable speed is required.

It is therefore an important object of this invention to provide a pump which is adapted to deliver a liquid at a constant supply, the pressure of the supply aecting the pumping action of the pump. More specically stated, the invention contemplates using the pressure built up by' the pump to regulate the amount of liquid drawn into the pump. In one application of my device in which a pair of meshed gears are used, the liquid on the pressure side of the pump is adapted to move one of the gears axially thereby making them more or less ei'cient depending on the 40 pressure of the liquid.

Another object of the invention is to provide adjusting means for regulating the relative movement of the pumping members. The adjusting means in the preferred form is resilient or yield- 45 ing'in which case the pressure of the liquid may be maintained practically constant or made to vary in proportion to the speed of the pump, depending on the type of yielding or resilient means employed and the static loading thereof.

The above and other novel features of the invention will appear' more fully hereinafter from the following detailed description when taken in conjunction with the accompanying drawing. It is expressly understood, however, that the draw- 55 ing is employed for purposes of illustration only and is not designed as a definition of the limits of the invention, reference being had for this purpose to the appended claims.

In the drawing, wherein similar reference characters refer to similar parts throughout the 5 several views:

Figure 1 is a sectional view of a pump illustrat- V ing a preferred form of my invention;

Figure 2 is a side elevation of the form shown in Figure 1; 10

'Figure 3 is a sectional view taken online 3--3 of Figure 1;

Figure 4 is a view showing in elevationa modied form of adjusting means for regulating the pumping means shown in Figure 1; 15

Figure 5 is a view illustrating the application of my invention to another type of pump in which an eccentric is used, parts being broken away and the cover removed;

Figure 6 is a sectional view taken on line E-S of Figure 5 showing the cover as applied thereto;

Figure 7 is a sectional view showing another modication of my invention in which an adjustable weight may be used for regulating the pumping means to obtain a. constant supply at variable speeds of the pump; and

Figure 8 is a sectional view on line 8-8 of Figure 7.

-in Figures 1, 2, and 3, is formed by two overlapping parallel bores 20 and 22. The head portion is provided with a bearing portion 24 in the 40 form of an extended boss and a screw-threaded opening 26. When the cover IIJ is secured to the base I2, the bearing 24 and the opening 26 are axially aligned with the bores 2D and 22 respectively. V 45 A driving shaft 28 is journalled in the bearing 24 and extends into the bore 20. Mounted on the lower end of the shaft 28 is a cylindrical member 30 which slidingly ts the inner periphery of the bore 20 and a portion of which extends into the 50 bore 22. A boss 32 on the cover IU is adapted to t the upper end of the bore 20 and is provided with a ,circular groove or cut-away portion 34, the periphery of which completes and forms a portion of the inner periphery of the bore 22 55 t .at its upper end. A rotor of theV same diameter -thickness of both gears.

as the bore 28, shown in this form as a toothed gear 88, is keyed to the shaft' 28' as at 88 and is -placed between the inner ends ot the boss 82 and the member 8 8. It will be understood that e shaft 28, member 38 and gear 88, when assembled in the cover, form a unit and that the inner ends of the boss 82 and member 88 seal the edges or side faces ci.' the gear forming liquid spaces between th'e teeth of the gear. f

Axially movable in the bore 22 is another rotor or toothed gear 48 of the same diameter as bore 22 which meshes with and is driven by the gear 88. On one side oi' the gear 48 there is provided a circular disc member 42 which slidingly its the bore 22 and groove or cut-away portion 84 in the boss 32. n the other side of the gear' 48, and in contact therewith there is provided a cylindrical member 44 having a circular groove or cut-away portion 48 which fits around the outer periphery of the member 88. 'The members 42 and 44 and the gear 48 are carried by a shaft 48 which may be an integral part of the member 42 and pinned to the member 44 as at 88 to prevent rotation. The gear 48 is free for rotation on the shaft 48 and the parts assembled :form a unit free vfor axial movement within the bore 22. An elemental passage or groove 82 is provided in the member 44 which forms a communication from the gear teeth circle on the gear 48 at a point angularly displaced fromwhere the gear teeth mesh, 'so that fluid may exert a piston pressure on the end face oi! the member 44, urging the same upward as illustrated in Figure 1, the under end surface of the member 44 and shaft 48 forming a piston.

Threaded inthe opening 28 is a screw 84 which adjustably tensions a spring 88 between the lower end of the screw land the upper surface of the circular disc member 42. A cap 88 `may be provided over the outer end ot the screw 84 serving as a lock to retain the screw in adjusted position.v

An inlet opening 88, communicating with the chamber formed by the two bores 28 and 22, admits liquid to the gears and they carry the liquid around, each in opposite directions, to the opposite side of the chamber where the liquid is delivered out through outlet opening 812; the meshing of the 'gears preventing a return of the liquid to the inlet openingA 88. At this point, it should be noted that the passage 82 in reality communicates with the outlet opening 82, and that the circular disc 42 is provided with a passage 84 forming a communication between the inlet opening 88 and the upper exposed face of the disc. v

In the operation of this form ofy my device a pressure is built up on the outlet side of the meshed gears. 'Ihe pressure is conducted through the passage 82 and below the member 44. When this pressure at this point becomes greater than the tension on the spring 88, previously adjusted to the proper tension, it moves the unit comprising member 42, gear 48 and member 44 axially upwardly, reducing" the engaging surface of the gears and reducing the pumping action.v In eil-ect it is the same as reducing the The groove 84 is provided in the member 42 to permit escapement of air or liquid which might be otherwise entrapped aovasvs f part oi' the screw 88. It will be understood that by turning the screw 88 I,the gear 48' may be f raised or lowered thereby reducing or increasing the eiective width of the gears or their pumping action. This form of the invention is best adapted for delivering a variable at will constan supply of liquid at aI constant speed. v i In Figures 5 and 6, there is shown an eccentri pump with a form of the present invention lappliedvthereto. The casing comprises a-head portion 18 and a base portion 12, each having flanges 14 adapted to be secured together by screws 18.

A chamber is provided in both members the same l being divided by a slidable plate 18' formlng a chamber 88 and a chamber 82. A slot '84 is formed in the wall of the chamber 82 to receive a sliding plate 88 resiliently urged toward the vcenter of the chamber by a at Z spring 88.

A driving member 88 is journalled in the base 12 and is in axial alignment with the chamber 82. At the inner end of the driving member 98 is a pin 82 eccentrically mounted thereon. Slidably mounted on the pin 82 and extending through an opening in the plate 18 is a cylindrical member 84. The plate 88 is resiliently urgedagainst the outer periphery of the member 84 forming compartments 88 and 98. An inlet opening 88 and an outlet opening |82 are providedrin the base 12 and are on opposite sides ci the plate 88 and slot 84.

It will be understood that as the driving member is rotated the compartments 88 and 88 increase and decrease in volume due to the eccentric movement of the member 84, and pump the liquid.

Mounted in the cover andin axial alignment with the driving member 88, there is illustrated a plunger |84 in engagement with the outer surface oi the member 84. A spring |88 resiliently urges the plunger |84 against the member 84 and an adjusting screw |88 permits a variable tension to be had on the spring |88. A lock nut ||8 secures the screw in adjusted position. A piston slotted to accommodate the plate 88 is provided withv a groove ||8 in the slot side wall adjacent the exhaust, and is axially movable in the chamber 82 with the member 84.

As the pressure in the pump builds up it is con; ducted to the outer surface ||2 of the piston through groove ||8, and the pressure moves the piston and member 84 against the tension o! the spring |88. The effective width or pumping action of the member 84 is reduced or increased depending on the tension of the spring 88, and the pressure behind the surface I I2.

In the forms shown in Figures 7 and 8 there V is illustrated` another modiiled form of a pump in which rotor members |4 are driven by meshed gears ||8. One of the rotors is provided with an annular piston flange 8 which fits a bore |28 and forms a seal between the compartment for the rotors and the opposite end. of the bore |28.

Members |22 form seals at the ends oi' the rotors opposite the annular flange on one of the rotors; the one in the bore |28 being axially slidable with the anged rotor therein. A shaft |24 axially slidable but splined in one of the gears ||6 moves the member and rotor axially in the bore |20 to vary the effective contact of the two rotors H4. In this form of the invention, means are provided for maintaining a constant pressure or supply at variable speeds of the pump since the pressure on the piston exceeds the pressure on the upper member |22, the area of the member |22 in the bore |20 being less than that of the piston I8 due to the cut-out portion. The means comprises a link |26 pivoted as at |28 to a bracket |30 on the side of the housing |32. "An adjustable weight |34 is placed on one end of the lever and the opposite end of the arm is yoked to the shaft |24 as at |36.

The weight provides a uniform pressure and does not increase its effect with increase in movement as in the case of a spring which is being compressed, and hence uniform pressure or -output may be obtained.

Though several embodiments of the invention have been illustrated and described it is to be understood that the invention is not limited thereto, but may be embodied in various mechanical forms and combinations as may be desired. As various changes in construction and arrangement of parts may be made, for example substitution of the yielding means of one modification for the resilient means of another, and other rearrangements, without departing from the spiit of the invention, as will be apparent to those skilled-in the art, reference will be had to the appended claims for a definition of the limits of the invention.

What is claimed is:

`1. In a gear pump, a casing, a drive pinion therein, an idler pinion meshing therewith, and having a circular piston on one side thereof and means for preventing rotation thereof and a cir.

cular cutaway piston onthe other side thereof, the said casing being recessed for rotary movement of said drive gear only, and recessed for rotary movement of said idler pinion and axial movement from its normal position in one direction only of said idler pinion'and pistons, said second named piston being cut away to closely clear said drive pinion, means for yieldingly urging said idler pinion into mesh with said driving pinion and in a direction toward the cutaway piston, an intake port leading towards the unmeshing teeth of said pinions, a discharge port leading away from the meshing teeth of said pinions, a port in the form of a groove on the outer surface of said first named piston leading from the unmeshing teeth to the space on the opposite side thereof, and a port in the form of a groove on the outer surface of said second named piston leading from the meshing teeth to the space on the opposite side thereof.

2. In a gear pump, a casing having a drive bore, an idler bore parallel therewith andslightly intersecting the drive bore, a drive shaft concentric to said drive bore, a pinion closely tting said r`drive bore and secured for rotation with said drive shaftand centrally located with respect to said drive bore, said drive bore being completely filled on one side 'of said pinion, and completely filled on the other side'of said drive pinion except for a space dened by the idler bore, an idler pinion in the idler bore slidable from full engagement with the drive pinion to a point of partial engagement towards the said other side of said drive pinion, a non-circular piston on the one side of said idler pinion having a `contour to t the idler bore except for the intersectl ing drive bore, and a circular piston on the other side of said idler pinion, means for preventing rotation of said circular piston, an intake passage to said pinions, a discharge passage from said pinions, a port through said circular piston directly connecting the intake passage with the space in the idler bore on the other side of said circular piston from said idler pinion and a port through said non-circular piston directly connecting the space in said idler bore on the other side of said non-circular piston with the discharge port, and yielding means urging the idler pinion axially into full mesh with the drive pinion.

' ANDREW 0. MCCOLLUM. 

